It is exactly the same meaning , but "Sorry " is in english , and "Pardon" is in french and both are a speech form of apologize ,being sorry , regreting something you have done or so .
If you happened to hear the word " Pardon" from a native english speaking person ,that is because maybe he or she lived in france , mingled with french people , there is always an interaction between different cultures , so some english speaking people would use words from french or italian for example .